Tape drive with self-expanding coils for sludge collector

ABSTRACT

Apparatus for taking up and paying out first and second ends of an endless loop of tape that has an intermediate section. A first reel connected to the first end carries a first coil of the tape. The fist coil extends from the first reel and is normally self-expanding and unwinding so as to unwind itself from the first reel. A second reel is connected to the second end for carrying a second coil of the tape. The second coil extends from the second reel and is normally self-expanding so as to unwind itself from the second reel. A drum supports both of the first and second reels for rotation in the same direction. Pulleys guide the intermediate section of the tape from the first reel to the second reel for moving a sludge collector. When the drum is rotated in a first rotary direction, the first coil tends to self-unwind from the first reel and the second coil is wound up on the second reel to move the intermediate section of the tape and the sludge collector. Upon rotation of the drum in a second rotary direction, the second coil tends to self-unwind from the second reel to apply tension to the tape and the first coil is wound up on the first reel to move the intermediate section of the tape and the sludge collector.

This is a divisional of co-pending application Ser. No. 321,440, filedon Mar. 9, 1989, now U.S. Pat. No. 4,927,537.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This application relates to drives for reciprocating equipment along awork path and more particularly to a reel system for winding up andpaying out two self-expanding coiled tapes to reciprocate equipmentalong a track for use in clarifier basins.

2. Discussion of Prior Art

In the past, clarifier basins have been provided with sedimentcollecting devices that move on a track fixed to the floor of the basin.In one such device, patented by applicant in U.S. Pat. No. 4,401,576, acarriage is provided for movement along the track. The carriage is movedby a stepping mechanism that grips the track and moves the carriagerelative to the track. Although such stepping mechanism has beencommercially successful, mechanisms that are located under water areinherently difficult to maintain because the track is located underwater where the sediment or sludge collects on the floor of theclarifier basin.

In other devices for removing sludge from the floor of clarifier basins,floats are pulled alternately in opposite directions across the surfaceof the clarifier basin. Pipes extend from the float to the floor forsludge collection. The floats are pulled by a cable that has first andsecond ends. The first end is wound in one direction on a winch and thesecond end of the cable is wound in the opposite direction on the winch,such that rotation of the winch in one direction unwinds the first endof the cable and winds up the second end of the cable to pull the floatin one direction across the basin. Reversing the direction of rotationof the winch reverses the direction in which the float is pulled acrossthe basin. In the device of this type disclosed in U.S. Pat. No.3,416,176 issued in 1968, the winch has a fixed diameter drum. Both thefirst and second ends of the cable are tightly wound on the drum of thewinch. In this device, if the travel of the float is long enough torequire the cables to wind on themselves and form more than one layer onthe drum, the length of cable unwound from the now larger diameter onthe drum will exceed that wound on the drum, which requires use ofspring-biased pulleys, for example, to compensate for the unequallengths.

In other clarifier basins that are provided with apparatus for removingsludge, the direction of movement of a bridge across the clarifier basinis reversed by reversing the direction of a drive motor. This occurs bytripping switches when the bridge reaches the end of its motion in aparticular direction. In other devices for removing sludge fromclarifier basins, an elongated power screw is mounted across the top ofthe clarifier basin. This screw is rotated by a motor. A ball nutactuator is threaded onto the power screw and is mounted on a carriageagainst rotation. When the motor rotates the power screw, the carriageis reciprocated over the top of the clarifier basin.

In other drives for reciprocating devices along a path, one end of acable is wound in one direction on a drum and the other end of the cableis wound in the other direction on the drum. In one such unit disclosedin U.S. Pat. No. 630,962 issued in 1899, the drum is provided with threesurfaces, the outer two of which surfaces are conical in shape forreceiving a pair of cables that are wound in a first direction. Theother surface, a central cylindrical drum, receives a sounding line thatis wound in a direction opposite to that of the cables. This unitrequires the use of cable guides that are provided on a lead screw forguiding the cables onto selected and controlled portions of the conicalsurfaces.

In the art of moving or lifting objects, the single drum of an ordinaryhoist has been provided with a ring that divides the single drum intotwo sections. In one such apparatus disclosed in U.S. Pat. No. 747,113issued in 1903, a button has been provided on such ring and is used forengaging a rope so that as both sections of the drum are rotated in thesame direction, one section of the drum winds up one length of ropewhile the other section of the drum unwinds another length of rope.

In other drives for positioning transducers along a longitudinal path,such as disclosed in U.S. Pat. No. 4,198,871 issued in 1980, a capstanis provided with a cylindrical surface to which opposite ends of aflexible, steel belt are secured. Those ends of the belt are wrapped inopposite directions on the capstan so that rotation of the capstan in agiven direction unwinds one end and winds up the other end. In thisdevice, those end are wound tightly on the capstan such that the beltdoes not become uncoiled when the direction of rotation of the capstanis changed.

In a swimming pool cleaning device disclosed in U.S. Pat. No. 2,646,889issued in 1953, a vertically extending guide rod is used to support acleaning head that is moved up and down within the swimming pool underthe action of a manually operated winch. Cables are wound in the samedirection on the winch such that rotation of the winch in a givendirection winds in both of the cables to lift the cleaning head.

In a high speed printer disclosed in U.S. Pat. No. 3,872,960 issued in1975, a motor drives a helically grooved pulley which has attached to itleft and right cable segments of equal length. The other ends of thecable segments are attached to a movable carriage. One pulley of thissystem is spring biased to remove any slack from either of the cableswhich might occur due to long term temperature drift. Thus, both cablesegments are held tight against the grooved pulley.

SUMMARY OF THE PRESENT INVENTION

In applicant's experience with devices for collecting sludge fromclarifier basins, driving devices located under water are difficult toperform maintenance on because they are under water. Thus, maintenancemust be performed when the basin is empty (and thus shut down) or adiver must go under water to make the repair. Attempts to mount suchdriving devices above the water level often result in using heavy powerscrews that interfere with operations conducted above the water level.When reels have been used for winding up cables that move such devices,complex drum shapes have been required to equalize the diameter of thecable on a full reel relative to that of an empty reel.

When a cable of such devices is being unwound from a reel and a cable isbeing wound onto another or the same reel, other spring biasingtechniques have been required to apply tension to both cables.Accordingly, there is still a need in the art of equipment, such assludge collectors, and moving in clarifier basins, for a simple,reliable drive located out of the liquid in the basin and operated byone motor, wherein no extra cable tensioning techniques and no complexdrum shapes are required.

An object of the present invention is to provide a new and improveddrive unit for reciprocating a carriage on a track, where the drive unitis remote from the carriage.

Another object of the present invention is to move a unit in liquidcontained in a clarifier basin using a single motor that is located outof the basin.

A further object of the present invention relates to a single motordriving separate reels on which steel tape is wound in oppositedirections, wherein the rotation of the reels in one direction permitsthe steel tape on one reel to self-expand into a loose coil that isrestricted in diameter.

An additional object of the present invention is to provide a pair offirst and second reels that are selectively connected to a common drumthat is rotated in either of two opposite directions by a common motor,wherein a first metal tape is wound on the first reel in a directionopposite to that in which a second metal tape is wound on the secondreel so that as the first metal tape is tightly wound on the first reelthe second metal tape self-expands into a loose coil to resist theunwinding of the second tape from the second reel.

A still further object of the present invention is to provide a wiperfor cleaning and drying a metal tape as it is wound onto a reel on whichthe metal tape self-uncoils after being wound into coil form.

Yet another object of the present invention is to stop a drive when acarriage reaches the end of a clarifier basin and, after pausing toallow the drive to stop, reversing the drive to move the carriage to theother end of the basin.

With these and other objects in mind, the present invention relates ingeneral to an apparatus for taking up and paying out first and secondends of an endless loop of tape that has an intermediate section. Afirst reel connected to the first end carries a first coil of the tape.The first coil extends from the first reel and is normallyself-expanding and unwinding so as to unwind itself from the first reel.A second reel is connected to the second end for carrying a second coilof the tape. The second coil extends from the second reel and isnormally self-expanding so as to unwind itself from the second reel.

A drum supports both of the first and second reels for rotation in thesame direction. A series of pulleys guides the intermediate section ofthe tape from the first reel to the second reel. A motor rotates thedrum in a first rotary direction so that the first coil tends toself-unwind from the first reel and the second coil is wound up on thesecond reel, which at that time functions as a take-up reel, to move theintermediate section of the tape toward the second reel and to draw thetape from the first coil that is self-expanding. The motor is effectiveto rotate the drum in a second rotary direction so that the second coiltends to self-unwind from the second reel to apply tension to the tapeand the first coil is wound up on the first reel, which at that timefunctions as a take-up reel, to move the intermediate section of thetape toward the first reel and to draw the tape from the second coilagainst the tension of the self-unwinding second coil.

When the ends of the tape are connected to a carriage of a sludgecollector that rides on a track in a clarifier basin, the tension fromthe self-unwinding coil opposes, but is less than, the tension caused bythe take up reel so that the loop of tape is held against the pulleyswithout using spring biasing techniques that may interfere with otheroperations in the clarifier basin.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention will beapparent from an examination of the following detailed descriptionswhich include the attached drawings in which:

FIG. 1 is a plan view of a rectangular clarifier basin provided with apair of sludge collectors driven by a tape drive of the presentinvention;

FIG. 2 is a vertical cross section taken along line 2--2 in FIG. 1illustrating the sludge collectors shown in FIG. 1 mounted forreciprocating movement on a floor of the clarifier basin;

FIG. 3 is a plan view of a second clarifier basin wherein a singlesludge collector is mounted for reciprocating motion along the bottom ofthe clarifier basin, showing a tape drive of the present invention formoving the single sludge collector;

FIG. 4 is a vertical cross-sectional view taken along line 4--4 in FIG.3 illustrating the clarifier basin shown in FIG. 3 with the tape driveaccording to the present invention;

FIG. 5 is a perspective view of one embodiment of the tape drive of thepresent invention, showing a pair of spaced reels mounted on a commonshaft, wherein resilient metal tape is shown self-expanded into coils onthe reels, where each coil is retained by a strap;

FIG. 6 is an end view of the tape drive of the present invention showingthe retainer strap extending around the expanded coil shown in FIG. 5for retaining the coil on one of the reels;

FIGS. 7A and 7B, when placed so that FIG.7A is on the left and FIG. 7Bis on the right, together form an elevational view of a secondembodiment of the tape drive of the present invention including spacedreels, each having a connecting ring for selective connection to a drumdriven by a pulley, where the left reel is shown in cross section;

FIG. 8 is a cross sectional view taken along line 8--8 in FIG. 1 showinga carriage of the sludge collector riding on a track supported on thefloor of the clarifier basin;

FIG. 9 is a cross-sectional view taken along the line 9--9 in FIG. 7Ashowing a connecting ring that is coupled to one of the reels forselective connection to the drum by a drive pin;

FIG. 10 is a partial cross-sectional view taken along line 10--10 inFIG. 7A showing a slot in the second hub for securing the second tape tothe second reel; and

FIG. 11 is a cross-sectional view taken along line 11--11 in FIG. 5showing a tape wiper for cleaning and drying one of the tapes as theyapproach the reels.

DETAILED DESCRIPTION

Referring now to FIGS. 1 and 2, a clarifier basin 20 is shown havinglateral walls 21 and left and right end walls 22 and 23. In FIG. 2, abottom or floor 24 of the basin 20 is shown. The basin 20 containsliquid 25 and particles 26 suspended in the liquid 25. The particles 26tend to settle to the floor 24 and form a layer of sludge 27. In FIG. 1a pair 28 of sludge collectors is shown, including a first sludgecollector 29 at the top of FIG. 1 and a second sludge collector 30 atthe bottom in FIG. 1. Each sludge collector 29 includes a track 31(FIGS. 2 and 8) mounted on a bracket 32 secured to the floor 24 of theclarifier basin 20. Carriages 33A and 33B ride along the track 31 andcarry a header pipe 34 connected to a suction hose (not shown). Thesludge collectors 29 and 30 may, for example, be constructed in themanner disclosed in applicant's U.S. Pat. No. 4,401,576 except for thestepping mechanism that is replaced by a tape drive 35 of the presentinvention.

The tape drive 35 is mounted at a common support location 36 andincludes a first tape 37 shown in FIG. 1 extending between the tapedrive 35 and a first end 38 of the first sludge collector 29. A secondtape 39 is shown connected between the tape drive 35 and a first end 40of the second sludge collector 30. A third tape 41 is connected tosecond ends 42 and 43 respectively of the sludge collectors 29 and 30. Aset of pulleys is provided for guiding the tapes 37, 39 and 41. Thefirst tape 37 extends downwardly from the tape drive 35, aroundrespective first and second pulleys 44 and 45 (FIG. 1), along a pathparallel to a longitudinal axis 46 (FIG. 1) of the clarifier basin 20and extends along a first of the tracks 31 (FIGS. 2 and 8) forconnection to the first end 38 of the first sludge collector 29.Similarly, the second tape 39 extends downwardly into the clarifierbasin 20, around third and fourth pulleys 47 and 48, respectively, andextends along a second of the tracks 31 (FIGS. 2 and 8) for connectionto the first end 40 of the second sludge collector 30. The third tape 41extends around fifth and sixth pulleys 49 and 50 from the second end 42of the first sludge collector 29 to the second end 43 of the secondsludge collector 30.

Referring to FIGS. 3 and 4, it may be understood that a third, singlesludge collector 51 is shown mounted along a central track 52 and ridingon a single carriage 53. A sludge collecting header pipe 54 of the thirdsludge collector 51 extends across the full width of the clarifier basin20 thus allowing use of only the one carriage 53. Also, only two tapes,in the form of the first tape 37 and the second tape 39, are required tomove the third sludge collector 51 on the track 52.

Although the first, second and third tapes 37, 39 and 41 respectively inFIGS. 1 and 2, and the respective first and second tapes 37 and 39 inFIGS. 3 and 4, are separately identified, they in effect form an endlessloop 56 that extends from the tape drive 35, around the various pulleys44, 45, 49, 50, 48 and 47 as shown in FIGS. 1 through 4, to therespective sludge collectors 29 and 30, or 51, and back to the tapedrive 35.

According to the principles of the present invention, the tape drive 35shown in FIGS. 1 and 2, and the same tape drive 35 shown in FIGS. 3 and4, is effective to pull in or wind up the first tape 37 onto a firstreel 57 (FIG. 3) and at the same time permit the second tape 39 to bepayed out or unwound from a second reel 58 (FIG. 3). In FIGS. 1 and 2,this operation advances a first carriage 33 of the first sludgecollector 29 toward the right end wall 23 nearest the tape drive 35 atthe location 36. Such movement of the first sludge collector 29 pullsthe third tape 41 around the respective fifth and sixth pulleys 49 and50 to pull the second sludge collector 30 away from the right end wall23 toward the left end wall 22 of the clarifier basin 20. In FIGS. 3 and4, the reeling in of the first tape 37 causes the third carriage 53 tomove toward the right end wall 23 of the clarifier basin 20 and thepaying out of the second tape 39 permits such movement of the thirdcarriage 53.

GENERAL DESCRIPTION: TAPE DRIVE 35 AND TAPES 37, 39 AND 41

Referring now to FIG. 5, a first embodiment of the tape drive 35 of thepresent invention is shown, and is referred to using the referencenumber 35A, whereas in FIGS. 6 through 10 a second embodiment of thetape drive 35 is shown and is referred to using the reference number35B. The tape drives 35A and 35B are the same except for the manner inwhich a drum 59 is driven. Accordingly, for purposes of description,when the tape drive 35 is referred to, the structure of the tape drives35A and 35B is the same.

The tape drive 35 includes the drum 59 and the respective first andsecond reels 57 and 58 that are mounted on the drum 59 for free rotationthereon. A first connecting ring 60 is attached to the first reel 57 anda second connecting ring 61 is attached to the second reel 58. Theconnecting ring 60 or 61 of a particular reel 57 or 58 selectivelycouples the reel to the drum 59 such that when that coupling ring, e.g.,the second coupling ring 61, is disconnected from the drum 59 the secondreel 58 can be rotated independently of the first reel 57 to index thesecond tape 39 to either tighten or loosen the second tape 39 on thesecond reel 58. As shown in FIG. 5, the first tape 37 is wound in afirst or clockwise direction (see arrow 62) around the first reel 57such that when the first reel 57 rotates clockwise (see arrow 62) thefirst tape 37 is wound onto or is taken up on the first reel 57. Thesecond tape 39 is shown wound in a second or counterclockwise direction(see arrow 63) around the second reel 58. As described in detail below,the first and second tapes 37 and 39 are formed from thin steel webs.Such tapes 37 and 39 have a characteristic of self-uncoiling from thecoiled configurations shown in FIG. 5, where the first tape 37 is shownformed into a first coil 64 on the first reel 37 and the second tape 39is shown formed into a second coil 65 on the second reel 58. In otherwords, this characteristic of the tapes 37 and 39 causes the coils 64and 65 to self-expand in diameter. When the drum 59 is not beingrotated, this self-uncoiling or expanding characteristic causes theexpanding coil 64 or 65 to apply tension on the respective tape 37 or 39which pulls on the end 38, 40, 42, or 43 of the carriage 33 to which itis connected. When the drum 59 is rotated in the counterclockwisedirection (see arrow 63) the first coil 64 of the first tape 37 becomesloose and the self-expanding characteristic causes the diameter of thefirst coil 64 to increase. To prevent the first coil 64 from expandingand becoming uncoiled from the first reel 57, a first retainer strap 66,shown in greater detail in FIG. 6, extends around 270° of the first reel57 and prevents the first coil 64 from becoming uncoiled and disengagedfrom the first reel 57. A similar second retainer strap 67 extendsaround the second reel 58 as shown in FIG. 6 for retaining the secondcoil 65 on the second reel 58 as the second coil 65 self-expands orself-uncoils upon rotation of the drum 59 in the clockwise direction(see arrow 62).

TAPE DRIVE 35-DETAILED DESCRIPTION

Referring to FIG. 5, the tape drive 35A is shown driven by a motor 68that drives a shaft 69. The shaft 69 is connected directly to the drum59.

In FIGS. 7A and 7B, the second embodiment of the tape drive 35B is shownincluding a first pulley 70 driven by a motor such as the motor 68 shownin FIG. 5. The first pulley 70 drives a standard belt 71 that extendsaround a second pulley 72 connected to the drum 59.

Referring in detail to FIG. 7, each tape drive 35 includes a pair 73(FIG. 7A) of respective left and right end brackets 74 (FIG. 7A) and 75(FIG. 7B) fixed to a metal plate 76 that serves as the base of the tapedrive 35. The metal base plate 76 is mounted (as shown in FIGS. 1through 4) on the right end wall 23 of the clarifier basin 20. As shownin FIG. 5, the base plate 76 is provided with a first slot 77 verticallyaligned with the first tape 37 as it extends downwardly from the firstreel 57, and a second slot 78 is vertically aligned with the second tape39 as it extends downwardly from the second reel 58. First and secondwiper assemblies 79 and 80 respectively are mounted on the base plate 76above each of the respective first and second slots 77 and 78 forcleaning the respective first and second tapes 37 and 39. A shaft 81extends through the end brackets 74 and 75 and is held to the endbrackets 74 and 75 by nuts 82 on opposite threaded ends 83 and 84 of theshaft 81. A bushing 85 is placed over each end of the shaft 81 to reducefriction between respective left and right ends 86 and 87 of the drum 59and the brackets 74 and 75, and between the shaft 81 and the drum 59.The bushing 85 may be made from acetal material sold by the duPontCompany under the trademark "Delrin."

The right end 87 of the drum 59 has a reduced outer diameter section 88that is slightly tapered to receive the second pulley 72. The secondpulley 72 is force fit over the reduced diameter section 88 of the drum59. The second pulley 72 is bolted to a larger outer diameter section 89of the drum 59 to secure it in driving engagement with the drum 59. Itmay be understood then, that the second pulley 72 rotates the drum 59 onthe shaft 81.

Each of the respective first and second reels 57 and 58 includes twoflanges, a left flange 90 and a right flange 91, that are mounted onopposite sides of a reel hub 92. The left or first reel 57 in FIG. 7A isattached to the first or left connecting ring 60. The left connectingring 60 is bolted to the right flange 91 of the first reel 57 to form anintegral unit comprising the two flanges 90 and 91, the hub 92, and thefirst connecting ring 60. The right or second connecting ring 61 of thesecond reel 58 (shown on the left in FIG. 7B) is bolted to the leftflange 90 of the second reel 58. As shown in FIG. 9 for the connectingring 60, and as is also applicable to the connecting ring 61, the ring60 has upper and lower cut-outs 93 and 94 and first and secondvertically extending bores 95 and 96 that are offset from a center 97 ofthe ring 60 or 61 to receive one of two index pins 98. The index pin 98extends through the bores 95 and 96 in the first connecting ring 60 intoone of two bores 99 (FIG. 9) and 100 (FIG. 7A) that extend through thedrum 59 in longitudinal alignment with the bores 95 and 96 in the firstring 60. The index pin 98 thus connects the first connecting ring 60 tothe drum 59 for rotating the first reel 57. Upon removal of a cotter pin101 (FIG. 9) from the index pin 98 and removal of the index pin 98 fromboth the drum 59 and the first connecting ring 60, the first reel 57 canbe rotated independently of the drum 59 to wind the first tape 37 ontothe first reel 57 or unwind the first tape 37 from the first reel 57 toadjust the position of the first sludge collector 29 along the track 31.To reconnect the drum 59 to the first connecting ring 60, the first reel57 is rotated to align the bores 95 and 96 of the first ring 60 with oneof the bores 99 or 100 of the drum 59, the index pin 98 is inserted intothose bores 95, 96 and 99 or 100 and the cotter pin 101 is inserted.

It is to be understood that the drum 59 and the shaft 81 extend axiallyacross FIGS. 7A and 7B, such that the drum 59 drives both of theconnecting rings 60 and 61 when the index pins 98 are inserted asdescribed above.

In addition to the bores 99 and 100 provided in the drum 59 for use withthe left or first index pin 98 and the first ring 60, third and fourthbores 102 and 103 (FIG. 7B) are provided in the drum 59 axially spacedfrom the bores 99 and 100. The second connecting ring 61 need only berotated one-half turn between aligning the bores 95 and 96 with one ofthe two bores 102 or 103 in the drum 59 and the second index pin 98 isinserted into the bores 95, 102 or 103, and 96 to connect the secondreel 58 to the drum 59.

RETAINER STRAPS 66 AND 67

Referring again to FIGS. 7A and 7B, the respective first and secondreels 57 and 58 and are shown in side-by-side relationship and havingthe index pins 98 placed in the bores 95, 96 and 99, and the bores 95,96 and 102, to connect each reel 57 and 58 to the drum 59 for rotationin unison around an axis 104. Referring also to FIG. 5, the second coil65 that is wound on the second reel 58 is shown having fewer turns andfor purposes of description the second reel 58 in FIG. 5 will bedescribed as being rotated counterclockwise (arrow 63) to wind thesecond tape 39 onto the second reel 58. Because the first reel 57rotates with and in the same direction as the second reel 58, andbecause there are many more turns of the first tape 37 on the first reel57 (as shown in FIGS. 5 and 7A), as the first reel 57 rotatescounterclockwise (arrow 63) the first tape 37 will quickly loosen andself-expand in diameter as shown in FIGS. 5, 7A and 7B to that of theouter diameter of the flanges 90 and 91.

The retainer straps 66 and 67 are the same. As shown in FIGS. 5, 6, 7Aand 7B, the retainer strap 66 is provided with a first end 105 (FIG. 6)that is secured by a bracket 106 to the base plate 76. The retainerstrap 66 extends from the base plate 76 vertically and at an angle of90° on the drum 59 engages and extends between the flanges 90 and 91 andaround the first reel 57 between those flanges 90 and 91 toapproximately a 360° angle on the drum 59. A bracket 107 secures asecond end 108 to the base plate 76. In a similar manner, the secondretainer strap 67 extends around the second reel 58 for retaining thesecond coil 65 when it assumes the expanded position described below.The retainer straps 66 and 67 are fabricated from the same material fromwhich the first and second tapes 37 and 39 are fabricated as describedbelow and are thus of sufficient tensile strength to withstand the forceof the coils 64 and 65 in their expanded configurations (e.g., the firstcoil 64 on the left in FIG. 7A).

TAPES 37 AND 39

The respective first and second tapes 37 and 39 are fabricated fromsteel having a thickness of from five to twenty thousandths of an inchand a width of from one to two and one-half inches. The length of therespective first, second and third tapes 37, 39 and 41 of course variesaccording to the particular distance between the location 36 at whichthe tape drive 35 is mounted on the wall 23 of the clarifier basin 20and the location of the particular sludge collector 29, 30 or 51 to beadvanced along the track 31. These tapes 37, 39 and 41 are fabricatedfrom rolled sheet steel stock having a normal rolled width of aboutforty-eight inches and are slit in a normal manner into the tapes 37, 39and 41 having the width of from one to two and one-half inches. Thesteel material is standard grade, stainless steel tape, providingcorrosion and abrasion resistance for use in the clarifier basin 20.

Using steel material having such specifications, FIG. 10 shows a firstend 109B of the second tape 39 placed in a slot 110 of the hub 92 andbent. The tape 37 is secured to the hub in the same way. With the indexpins 98 removed from the bores 95, 96 and 99 or 102, for example, thereels 57 and 58 are then rotated while tension is placed on the tapes 37and 39 so that the tapes 37 and 39 become coiled tightly on therespective reel 57 and 58. The outer diameters of the coils 64 and 65are selected according to which coil 64 or 65 is to initially have thelarger diameter (see FIGS. 5, 7A and 7B where the first coil 64 has thelarger diameter). The self-expanding or self-unwinding characteristic ofthe steel tapes 37 and 39 causes the coils 64 and 65 of such tapes 37and 39 to tend to unwind into a flat, straight position as soon astension is relieved. For example, if the first tape 37 is wound aroundthe first hub 92 into the first coil 64, relieving the tension thatholds the first tape 37 in the shape of the tightly wound first coil 64allows the first coil 64 to self-expand or unwind by itself. The forceof the self-unwinding of the first tape 37 is such that the first tape37 will tend to be pulled upwardly through the first slot 77 in the baseplate 76 and thus apply tension on the first tape 37 as it extendsaround the pulleys 44 and 45. In the example shown in FIG. 3, with thefirst tape 37 connected to a right end 112 of the carriage 53 and thesecond tape 39 connected to a left end 111 of the carriage 53, suchuncoiling force of the first tape 37 is overcome by the force of thesecond tape 39 as it is wound onto the second reel 58. It may beunderstood then, that as the second tape 39 is wound onto the secondreel 58, the self-uncoiling force of the first coil 64 is effective tohave the first tape 37 resist the force of the second tape 39 that movesthe carriage 53 along the track 31, such that both the respective firstand second tapes 37 and 39 are in tension without the use of any othersprings or tensioning devices.

TAPE WIPERS 79 AND 80

Referring now to FIGS. 5 and 11, the tape wipers 79 and 80 are shownmounted on the base plate 76 over each of the respective slots 77 and78, the slot 77 being shown in FIG. 10. The tape wipers 79 and 80include a first wiper block 113 and a second wiper block 114 that areslidable on the base plate 76 toward and away from each other. Z-shapedbrackets 115 are secured, as by a screw 116, to the base plate 76 andhave an upper lip 117 that extends over each of the first and secondwiper blocks 113 and 114 to hold them on the base plate 76, yet allowthem to slide thereon. Ends 118 of the brackets 115 extend around thefirst and second wiper blocks 113 and 114 to limit the extent of thehorizontal travel of the first and second wiper blocks 113 and 114. InFIG. 11, the first and second wiper blocks 113 and 114 are shown havingopposed wiper edges 119A and 119B that form a tape receiving slot 120that is vertically aligned with the slot 77. The tape wiper 80 for theslot 78 is similarly positioned relative to the slot 78. The tapereceiving slot 120 has a variable width to permit initial feeding of therespective first or second tape 37 or 39 into the tape receiving slot120 and then into the respective slot 77 or 78 from the respective firstreel 57 or second reel 58. The first and second wiper blocks 113 and 114are urged toward each other by springs 121 that urge heads 122 of bolts123 out of large diameter bores 124 formed in the first wiper block 113.Smaller diameter bores 125 are aligned with the large diameter bores 124and receive the bolts 123, which extend into tapped holes 126 in thesecond wiper block 114. By rotating the bolts 123 and threading themfurther into or out of the tapped holes 126, there is either more orless force applied by the springs 121 urging the first and second wiperblocks 113 and 114 toward each other. This force may be adjusted in therange of five to twenty pounds. The tapes 37 or 39 are thus squeezedbetween the wiper edges 119A and 119B, which scrape the liquid 25, theparticles 26 and the sludge 27 from the tapes 37 and 39 so that thetapes 37 and 39 are clean and relatively dry as they travel to therespective reels 57 and 58. The wiper blocks 113 and 114 are fabricatedfrom hard plastic, such as PVC or acetal (sold by the duPont Companyunder the trademark "Delrin"), which has the required abrasionresistance and hardness to effectively wipe the tapes 37 and 39 cleanand relatively dry.

With the respective first and second tapes 37 and 39 clean andrelatively dry as they advance onto the respective reels 57 and 58, theself-uncoiling or expanding action of the tapes 37 and 39 is notinterfered with by the liquids 25, the particles 26 or the sludge 27.

SLUDGE COLLECTORS 29, 30 AND 51

Each sludge collector is a standard unit such as that disclosed inapplicant's U.S. Pat. No. 4,401,576, except that the stepping mechanismshown in that patent is not used. Instead, second ends 109A (FIG. 4) ofthe respective first and second tapes 37 and 39 are connected to therespective carriages 33A, 33B and 53. The carriages 33A, 33B and 53carry a vacuum hose (not shown) that is connected to header pipes 34that draw the sludge 27 and the liquid 26 from the floor 24 of theclarifier basin 20.

REVERSING CONTROL FOR MOTOR 68

Referring to FIGS. 3 and 4, when the sludge collector 51 has moved tothe right wall 23, the motor 68 changes rotational direction. Duringthat change in direction, the second tape 39 that was previously intension because of the counterclockwise rotation of the motor 68, nowloosens as the motor 68 starts to turn clockwise (arrow 63). With suchloosening of tension on the second tape 39, the second tape 39self-uncoils and assumes a diameter equal to about that of the diameterof the flanges 90 and 91 such that the second coil 39 engages the secondretainer strap 67. Also, as the motor 68 started to rotate clockwise thefirst coil 64 was initially at the expanded diameter equal to that ofthe diameter of the flanges 90 and 91. Continued clockwise rotation ofthe motor 68 rotates the first reel 57 and causes the first hub 92 totighten the turns of the first coil 64 so that the diameter of the firstcoil 64 becomes smaller until it becomes tightly wound. The third sludgecollector 51 then starts to move to the right in FIG. 3 as the tensionon the first tape 37 overcomes the opposite tension of the self-uncoiledsecond tape 39. When the sludge collector 51 has moved to the left wall22, the motor 68 again changes direction. The same directional changecycling applies with respect to the sludge collectors 29 and 30 shown inFIGS. 1 and 2, with those collectors 29 and 30 moving in oppositedirections at each reversal of the motor 68.

The reversing of the motor 68 is controlled by sensing bolts 127 (FIG.7A) on a left end 128 of the reel 57. For this purpose, a proximitylimit 129 switch is mounted on the left end bracket 74. The switch 129may be Model 112120 sold by General Equipment Manufacturing Company as a"GO" switch. The switch 129 has contacts 130 that are normally open inresponse to the force of a magnet 131. When the drum 59 rotates, thebolts 127 move through the path of the magnetic flux of the magnet 131and weaken the flux so that the contact 130, which is a spring biased Cform contact, moves and closes a circuit 133 to generate a countingpulse 134. The counting pulse 134 is applied to a programmable logiccircuit 135 that stores the number of pulses 134. The number of bolts127 counted is related to the number of revolutions of the reels 57 and59 and thus to the position of the sludge collectors 29, 30 and 51 onthe tracks 31. Thus, for example, when the sludge collector 51 in FIG. 3reaches the right end 23 of the clarifier basin 20, the logic circuit135 will have stored a pre-determined number of pulses 134. The logiccircuit 135 is programmed in a standard manner to generate a stop signal136 in response to the storage of that number of pulses 134. Two secondsafter the stop signal 136, the logic circuit 135 generates aforward/reverse signal 137. A motor control 138 (FIG. 5) for the dcmotor 68 causes the motor 68 to stop in response to the stop signal 136,and to reverse its rotational direction in response to theforward/reverse signal 137. The logic circuit 135 then resets its pulsestorage to zero. This cycle is repeated as the motor 68 operates in theopposite rotational direction, e.g., in the counterclockwise direction(arrow 63) FIG. 5.

It is to be understood that when the carriage 53 is at the right wall23, the first reel 57 has wound the first tape 37 tightly onto the firsthub 92, whereas the second coil 65 has self-expanded on the second reel58 and under tension therefrom has supplied the second tape 39 to permitthe carriage 53 to move to the right wall 23. As the motor 68 isreversed as described above, the two second delay between the stopsignal 136 and the forward/reverse signal 137 allows the respectivefirst and second tapes 37 and 39 to stabilize and stop on the respectivereels 57 and 58. The carriage 53 also stops. As the motor 68 reversesits rotational direction, the tension from the first tape 37 on thefirst hub 92 is relieved and, as described above, the first coil 64self-expands and applies force on the right side 112 of the carriage 53.The motor 68 causes the second reel 58 to wind in the second tape 39 andtightly wind the second coil 65 on the second hub 92. When the secondcoil 65 is tightly wound, the force of the second tape 39 on the leftside 111 of the carriage 53 overcomes the force from the tension of thefirst tape 37 on the right side 112 of the carriage 53, and the carriage53 moves to the left in FIG. 3. This reversing cycle occurs again, inreverse, when the carriage 53 reaches the left wall 22 of the basin 20.

While the preferred embodiments have been described in order toillustrate the fundamental relationships of the present invention, itshould be understood that numerous variations and modifications may bemade to these embodiments without departing from the teachings andconcepts of the present invention. Accordingly, it should be clearlyunderstood that the form of the present invention described above andshown in the accompanying drawings is illustrative only and is notintended to limit the scope of the invention to less than that describedin the following claims.

What is claimed is:
 1. In an apparatus for moving equipment in aclarifier basin provided with a track and a carriage movable on saidtrack for carrying said equipment, said carriage having a first end anda second end, the improvement comprising:a first thin metal tapeattached to said first end of said carriage, said first tape having acharacteristic of resisting being rolled into a first coil such thatsaid first tape tends to uncoil itself; a second thin metal tapeattached to said second end of said carriage, said second tape having acharacteristic of resisting being rolled into a second coil such thatsaid second tape tends to uncoil itself; a first reel having a first hubsecured to said first tape for forming said first coil in said firsttape; a second reel having a second hub secured to said second tape forforming said second coil in said second tape; a drum releasably securedto each of said first and second reels for rotating said first andsecond reels clockwise to wind said first tape on said first hub andunwind said second tape from said second hub, said drum also rotatingsaid first and second reels counterclockwise to wind said second tape onsaid second hub and unwind said first tape from said first hub; saidunwound first and second tapes tending to uncoil themselves to form saidrespective first and second coils having increased diameters to applytension on said respective first and second tapes tending to pull saidtapes toward their respective reels; a first retainer strap extendingaround a portion of said first reel in engagement with said first coilthat has said increased diameter for retaining said first coil on saidfirst reel; and a second retainer strap extending around a portion ofsaid first reel in engagement with said second coil that has saidincreased diameter for retaining said second coil on said second reel;said tendency of said first tape to uncoil being effective to applytension to said first tape that applies a resistive force to said firstend of said carriage; said tendency of said second tape to uncoil itselfbeing effective to apply tension to said second tape that applies aresistive force to said second end of said carriage; said winding ofsaid first tape on said first hub being effective to overcome saidresistive force on said second end of said carriage and move saidcarriage in a first direction on said track, said carriage moving insaid first direction being effective to unwind some of said second coilfrom said second reel as said clockwise rotation of said second reelpermits said second coil to uncoil itself and apply said tension to saidsecond tape; and said winding of said second tape on said second hubbeing effective to overcome said resistive force on said first end ofsaid carriage and move said carriage in a second direction on saidtrack, said carriage moving in said second direction being effective tounwind some of said first coil from said first reel as saidcounterclockwise rotation of said first reel permits said first coil touncoil itself and apply said tension to said first tape.
 2. In a systemfor collecting sludge from a floor of a clarifier basin, said basinhaving opposed first and second walls for containing liquid andparticles suspended in said liquid, said suspended particles beingsettleable to said bottom to form said sludge, said clarifier basinincluding a guide track mounted on said bottom, said clarifier basinfurther including a carriage movable on said guide track between saidopposite first and second walls of said basin, said carriage havingmeans mounted thereon for collecting the sludge from said bottom, saidcarriage having a first end and a second end; the improvementcomprising;a first thin metal tape having a first end connected to saidfirst end of said carriage, said first tape having a second end andhaving a characteristic of resisting being rolled into a coil; a secondtape having a third end connected to said second end of said carriage,said second tape having a fourth end and having a characteristic ofresisting being rolled into a coil; pulley means for guiding said firstand second tapes from said respective first and second ends of saidcarriage to a common location; tape drive means mounted at said commonlocation for winding in said second end of said first tape and payingout said fourth end of said second tape to move said carriage on saidtrack between said first and second walls of said clarifier basin, saidtape drive means including: first reel means connected to said secondend of said first tape for winding said first tape thereon when saidfirst reel means rotates in a first direction; second reel meansconnected to said fourth end of said second tape for winding said secondtape onto said second reel means upon rotation of said second reel meansin a second direction opposite from said first rotational direction;drum means mounted at said common location and releasably connected toeach of said first and second reel means for rotating said first andsaid reels means together in either of said first or second rotationaldirections, rotation of said first and second reel means in said firstrotational direction being effective to permit said first tape to uncoilitself on said first reel means to form a first enlarged coil on saidfirst reel means and to tighten said second tape on said second reelmeans to wind in said second tape and move said carriage toward saidsecond end of said clarifier basin, said first enlarged coil beingeffective to release said first tape under tension that tends torestrain said carriage from moving toward said second wall, saidrotation of said first and second reel means in said second rotationaldirection being effective to reduce the size of said first coil on saidfirst reel and tighten said first tape on said first reel to wind saidfirst tape onto said first reel and move said carriage toward said firstwall and to permit said second tape to uncoil itself on said second reelmeans to form a second enlarged coil that applies force to said carriagetending to restrain said carriage from moving from said second walltoward said first wall of said basin means; and means extending aroundat least a part of the outside of each of said first and second reelmeans for retaining each of said first and second enlarged coils on saidrespective first and second reel means.
 3. In an apparatus forreciprocating equipment along a track mounted on a floor of a clarifierbasin between a first wall and a second wall, said apparatus including afirst pulley mounted on said floor adjacent said first wall and secondand third pulleys mounted on said bottom adjacent said second wall, saidtrack extending between said first pulley and said second and thirdpulleys, a carriage carrying said equipment and mounted on said trackfor movement between said first and second walls, said carriage having afirst end nearest said first wall and a second end nearest said secondwall, and a support plate mounted on said clarifier basin; theimprovement comprising:said support plate having a first slot and asecond slot spaced from said first slot; means for mounting said supportplate on said clarifier basin above said second and third pulleys; afirst thin metal tape extending through said first slot, around saidsecond pulley and said first pulley and being attached to said first endof said carriage, said first tape having a characteristic of resistingbeing rolled into a first coil such that said first tape tends to uncoilitself; a second thin metal tape extending through said second slot,around said third pulley and attached to said second end of saidcarriage, said second tape having a characteristic of resisting beingrolled into a second coil such that said second tape tends to uncoilitself; a first reel having a first hub secured to said first tape forforming said first coil in said first tape before said first tapeextends through said first slot; a second reel having a first hubsecured to said second tape for forming said second coil in said secondtape before said second tape extends through said second slot; a drumreleasably secured to each of said first and second reels for rotatingsaid first and second reels clockwise to wind said first tape on saidfirst hub and unwind said second tape from said second hub, said drumalso rotating said first and second reels counterclockwise to wind saidsecond tape on said second hub and unwind said first tape from saidfirst hub; said unwound first and second tapes tending to uncoilthemselves to form said respective first and second coils havingincreased diameters to apply tension on said respective first and secondtapes extending through said respective first and second slots; a firstretainer strap having a first end secured to said support plate,extending around said first reel in engagement with said first coil thathas said increased diameter and having a second end secured to saidsupport plate to limit said diameter and retain said first coil on saidfirst reel; and a second retainer strap having a first end secured tosaid support plate, extending around said first reel in engagement withsaid second coil that has said increased diameter and having a secondend secured to said support plate to limit said diameter and retain saidsecond coil on said second reel.
 4. In an apparatus according to claim3, the improvement further comprising:said tendency of said first tapeto uncoil being effective to apply tension to said first tape thatapplies a resistive force to said first end of said carriage; saidtendency of said second tape to uncoil itself being effective to applytension to said second tape that applies a resistive force to saidsecond end of said carriage; said winding of said first tape on saidfirst hub being effective to overcome said resistive force on saidsecond end of said carriage and move said carriage in a first directionon said track, said carriage moving in said first direction beingeffective to unwind some of said second coil from said second reel assaid clockwise rotation of said second reel permits said second coil touncoil itself and apply said tension to said second tape; and saidwinding of said second tape on said second hub being effective toovercome said resistive force on said first end of said carriage andmove said carriage in a second direction on said track, said carriagemoving in said second direction being effective to unwind some of saidfirst coil from said first reel as said counterclockwise rotation ofsaid first reel permits said first coil to uncoil itself and apply saidtension to said first tape.
 5. Apparatus for reciprocating clarifierequipment along a track mounted in a clarifier basin said equipmenthaving a first end and a second end, said basin provided with a firstpulley on the side of said equipment nearest said first end and with asecond pulley on the side thereof nearest said second end, comprising:afirst reel having a first hub provided with a first transverse slot; afirst metal tape having a first end and a second end, said first endbeing connected to said first end of said equipment, said first tapeextending around said first pulley to said first reel, said second endof said first tape being received in said first slot; a second reelhaving a second hub provided with a second transverse slot; a secondmetal tape having a first end and a second end, said first end beingconnected to said second end of said equipment, said second tapeextending around said second pulley to said second reel, said second endof said second tape being received in said second slot; a drum formounting each of said first and second reels for clockwise andcounterclockwise rotation, said clockwise rotation of said first reelbeing effective to wind said first tape on said first hub into a firstcoil; means for releasably and separately connecting said first andsecond reels to said drum to permit said drum to rotate said first reeland form said first coil while said second reel is not rotated; saidfirst tape having a characteristic of uncoiling, said characteristicbeing effective to apply tension tending to pull said first tape tightlyaround said first pulley and pull said first end of said first tapetoward said first reel; means for rotating said drum counterclockwise towind said second tape on said second hub into a second coil and to applytension to said second tape, said tension exceeding said tension on saidfirst tape to pull on said second end of said equipment and move saidequipment in a first direction on said track, said counterclockwiserotation being effective to unwind some of said first coil from saidfirst hub, said uncoiling characteristic of said first tape beingeffective to continue to apply said tension tending to pull said firsttape tightly around said first pulley; and a first strap extendingpartly around said first reel in engagement with said first coil tolimit the extent to which said first tape uncoils in response to saiduncoiling characteristic of said first tape.
 6. Apparatus according toclaim 5, further comprising:said second tape having a characteristic ofuncoiling, said characteristic being effective to apply tension tendingto pull said second tape tightly around said second pulley and pull saidsecond end of said second tape toward said second reel; said rotatingmeans being effective to rotate said drum clockwise to again wind saidfirst tape on said first hub to form said first coil and to applytension on said first tape that exceeds said tension on said second tapefrom said uncoiling characteristic of said second tape, said tension onsaid first tape being effective to pull on said first end of saidequipment and move said equipment in a second direction on said track;and a second strap extending partly around said second reel inengagement with said second coil to limit the extend to which saidsecond tape uncoils in response to said uncoiling characteristic of saidsecond tape.
 7. Apparatus according to claim 5, in which:said drum has alongitudinal axis and at least one bore formed therein perpendicular tosaid axis; and said connecting means including a first ring connected tosaid first reel and rotatable freely on said drum, and a second ringconnection to said second reel and rotatable freely on said drum, eachof said first and second rings having an aperture formed therein, saidrings being rotatable on said drum to align said aperture with said boreof said drum, said connecting means further including an index pin foreach of said first and second rings, one of said index pins beinginsertable into said aligned bore and aperture to form a releasabledriving connection between said drum and one of said first and secondrings to rotate said first or second reel attached to said respectivefirst or second ring.